The mammalian laboratory will continue to develop a psychophysically based account of somatosensory interactions by utilizing similar stimulus paradigms in studies of both humans and experimental animals to correlate psychophysical and electrophysiological findings. Particular attention will be devoted to two specific paradigms called masking and enhancement which deal respectively with the capability of conditioning skin stimuli to either elevate or reduce the threshold for detecting the presence of nearby test stimulus. During this grant period our work will focus on replicating our studies of masking and enhancement using monkeys instead of cats. In addition, further mapping of masking and enhancement, psychophysical functions, will be carried out on humans. In the work on Aplysia, we plan to continue describing the specific relationship between individual cells and behavior, and to formulate general rules relating different patterns of interconnections to specify types of behavior. Particular attention will be devoted to a cellular analysis of inking behavior (an all-or-none fixed act).